In the present proposal the Third Gordon Research Conference on Periodontal Diseases to be held in July, 1985, is outlined. The Conference is organized to bring together scientists interested in research in the clinical and basic science aspects of periodontal diseases. The Conferences are held for 4 1/2 days and include formal papers with ample discussion. The Gordon Conferences are unique in stimulating progress in research since the participants are housed together away from urban distractions, take all of their meals together and have, in addition, at least five hours each day for informal discussion outside of the meeting room. This provides the opportunity for both young as well as experienced basic and clinical scientists to mingle and discuss formally and informally, and at length, certain aspects of the frontier of our knowledge in periodontal diseases. The topics chosen for discussion are considered to be important by the organizing committee, and in many of these areas knowledge is lacking or there is controversy. Also, areas were chosen with the clear potential for clinical application. Periodontal research is at a point where discussion between clinical and basic scientists is of importance to preventive and therapeutic approaches. Hence, a combination of both clinical and basic science sessions is proposed. Financial support is requested for payment of travel expenses for some of the invited speakers and discussants. No individual will receive more than partial financial support and no honoraria or salaries will be paid.